Let m and n (m < n) be the roots of the equation x2 – 16x + 39 = 0. If four terms p, q, r and s are inserted between m and n to form an AP, then what is the value of p + q + r + s ?
29
30
32
35
A geometric progression (GP) consists of 200 terms. If the sum of odd terms of the GP is m, and the sum of even terms of the GP is n, then what is its common ratio ?
m/n
n/m
m + (n/m)
n + (m/n)
If the roots of the equation
a(b - c)x2 + b (c – a)x + c(a - b) = 0
are equal, then which one of the following is correct ?
a, b and c are in AP
a, b and c are in GP
a, b and c are in HP
a, b and c do not follow any regular pattern
C.
a, b and c are in HP
Here it is given that the roots of the given equation are equal than discriminant (D) = 0
Where discriminant (D) = (coefficient of x)2 – 4(coefficient of x)(coefficient of x0)
i.e, [b(c – a)]2 – 4[a(b – c)][c(a – b)] = 0
[b(c – a)]2 = 4[a(b – c)][c(a – b)] ... (i)
Assume the value of a, b and c which are in AP, GP, HP one by one and check which one is satisfy the result
It is very difficult to solve this and time consuming, so just try to do it by hit and trail method
When you assume the value a, b, c as 2, 3 and 6 respectively
Then, these value s will satisfy the equation (i), hence as 2, 3 and 6 are in H.P, so we can say that a, b and c will be in H.P
Option C is correct.
Arithmetic meanof 10 observation is 60 and sum of squares of deviations from 50 is 5000. What is the standard deviation of the observation ?
20
21
22, 36
24, 70
If (1 + 2x – x2)6 = a0 + a1x + a2x2 + ... + a12x12, then what is a0 – a1 + a2 – a3 + a4 - ... + a12 equal to ?
32
64
2048
4096